The term "spray devices" is used in general to cover an assembly constituted by a receptacle and a pump mounted on the receptacle for extraction and projection purposes. The invention relates more particularly to such spray devices in which the pump is of the precompression type including a needle valve having a spring holding it against its seat which is formed on the axis of a delivery piston, with the characteristics of the spring determining the amount of precompression. One such pump is described, for example, in American Pat. No. 4,025,046 and in French patent number 2,305,241.
In such a spray device, as increasing quantities of the substance to be sprayed are expelled, the volume previously occupied thereby is generally filled With air. However, with some substances, e.g. perfumes and medicines, contact with air must be avoided. In such cases, a gas, such as nitrogen for example, is inserted under pressure into the receptacle (which is deliberately only partially filled with the substance to be sprayed in order to leave room to receive the gas). As the substance is sprayed out, the nitrogen expands and occupies the volume left empty. This opposes the penetration of air into the receptacle. In addition, pump priming and filling are enhanced. A difficulty consists in injecting the nitrogen after the receptacle has been filled with liquid and the pump has been crimped onto the receptacle.
Various different means and methods have already been proposed for injecting gas into the receptacle. The methods used suffer from drawbacks, due above all to the length of time taken by the gas filling operation, and also to the size of the machines used for performing the methods.
The present invention seeks to provide simple means enabling a receptacle having a precompression pump crimped thereon to be rapidly filled or emptied, with gas or with liquid. The idea is to provide a pump with apparatus for ensuring that a fluid (a gas, a liquid, a paste, etc.) can flow either from the outside towards the inside of the container or from its inside towards its outside, with the path used for that purpose being permanently shut off either on the first occasion that the piston is actuated, or else by some other external action.